This would be a step backwards. The 300 WSM shoots bullets of equal weight, but much better ballistic coefficients to the same speeds. At the muzzle they offer exactly the same energy levels, but beyond 50 yards the 300 WSM has the advantage. The longer the range, the bigger the gap becomes. The better .30 caliber bullets out penetrate at any range. The .017" difference in bullet diameter is irrelevant.
The choice of .30 caliber bullets is almost unlimited. .325 bullets are hard to find and virtually no choices in good bullets.
First of all:
It isn't a 0.017" difference in bore size or groove diameter. It's 0.015". ".325 WSM" is a name. The actually groove diameter and bullet diameter is 0.323". The fact that you don't even know what diameter the bullets are really makes me wonder if you have EVER dealt with ANY 8mm cartridge. Anyway....
If you compare bullets of the same style and weight, but different calibers, you will
obviously have a different BC. That's the way it works.
If you want to compare same weight bullets across multiple calibers, we can do that, but by the time we get to 180 gr .17 caliber bullets (with their insane BCs), it'll be a little ridiculous.
Bullet selection cannot be arbitrarily labeled as "unlimited" or "limited", without discussing the intended purpose of the rifle. Attempting to do so, without that information, is a waste of time.
Regardless...
If you're shooting 150 gr and "165" gr bullets in a .325 WSM, you
are wasting the cartridge's potential. If you aren't shooting 190-250 gr bullets in a .325 WSM, it's a waste of powder.
Don't like the 8mm bore size? Don't buy one.